Method for flame hardening or annealing metal



- Aug. 30, 1949. J. J. CROWE METHOD FOR FLAME HARDENING, OR ANNEALING METAL Filed Feb. 24. 1944 v 2 Sheets-Sheet l /0XYGEN ,4 INVENTOR.

ATTORNE Y5 Aug. 30, 1949. J. J. cRow 2,480,287

METHOD FOR FLAME HARDENING'OR ANNEALING METAL Filed Feb. 24. 1944 2 Sheets-Sheet 2 IN V EN TOR.

A T TORNE Y5 Patented Aug. 30, 1949 UNITED STATE METHOD FOR FLAME HARDENIN G OR ANN EALIN G METAL John J. Crowe, Westfield, N. J., assignor to Air Reduction Company, Incorporated, a corporation of New York Application February 24, 1944, Serial No. 523,682 6 Claims. (01. 148-2156) This invention relates to the art of flame hardening and annealing the surface portion of metal objects.

In flame hardening or annealing metal it is desirable to control the depth of heat penetration into the work-piece and at times to effect deep penetration of heat without burning or melting the surface of the work-piece. The principal ob 'ject of the invention is to provide an improved method of flame hardening or annealing metal bywhich this is made possible.

'When deep heat penetration into the workpiece is desired there would be danger of melting or burning the surface of the work-piece if it were attempted to produce the deep penetration by a single application of the flames to each unit area of the surface long enough or with a high enough heat intensity to cause the heat to reach the desired depth in the work-piece.

In accordance with this invention the flame system which is employed to heat the work-piece is moved over its surface with a sweeping motion, i. e., so that it has a forward and backward movement with the forward stroke always longer than the rearward stroke whereby the flame system has a net forward travel. Thus, during movement of the flame system over the surface of the work-- piece there is an intermittent application of the flames to each unit of area of the work surface which causes the heat to soak into the work-piece to the depth desired without danger of burning or melting its surface. a

" The accompanying drawings illustrate the method and show two forms of novel apparatus,

either of which is adapted for use in carrying out the method.

In the drawings:

Figure 1 is an explanatory view illustrating in perspective how the flame system is moved over the surface of a work-piece when it is heattreated in accordance with the improved method;

Fig. 2 is a side elevation of one form of apparatus embodying the invention and which is adapted to carry out the method;

Fig. 3 is a plan view of the apparatus shown in Fig. 2;

Fig. 4 is a side elevation of a modified form of apparatus intended for use in the heat treatment of metal objects while being rotated in a bench lathe; I

Fig. 5 is a plan view of the apparatus shown in Fig. 4;

Fig. 6 is a vertical section taken on the line B'-6 of Fig. 5; and

' ber of times that the flames are applied to each Fig. 7 is a side elevation of a portion of another modified form of the apparatus.

The flame system is preferably produced by a gas torch, such as an oxy-acetylene heating torch, the tip of which is indicated at T in Fig. 1. In this figure the work-piece whose surface is to be heat treated is represented at W. When heat treating the surface portion of the work-piece according to my method, the torch is not moved over its surface with a continuous forward motion in the customary manner but is caused to move over it as indicated by the arrows in Fig. 1. For instance, if the torch is to be moved over the work-piece from left to rightas viewed in Fig. 1 the torch is given a series of forward strokes, relative to the work-piece as indicated by the long arrows I, 3, 5, etc., and a series of intervening rearward and shorter strokes, as indicated by the short arrows 2, 4, etc. The long arrows indicate the points reached successively by the torch on its forward strokes and the short arrows indicate the points reached successively by the torch on its rearward strokes. Thus the torch is moved with a sweeping motion and since the forward strokes I, 3, 5, etc., are longer than the rearward strokes 2, 4, etc., there is a net forward travel of the torch throughout the length of the work-piece. In this way the flames are applied intermittently to each unit of area of the work surface to elfect penetration of the heat to the desired depth. The num unit of area of the work surface and the interval of time that elapses between successive applications to such unit of area depend on the speed of movement of the torch in each direction, the length of the forward strokes, and the length of the rearward strokes relative to the forward strokes. By a proper correlation of these factors the flame system is moved from each unit area of the work surface to the next unit area before the preceding unit area has reached a burning or melting temperature and the work surface is heated to the desired extent and to the desired depth without damage thereto.

One formof apparatus for giving the desired motion to the torch is shown in Figs. 2 and 3. Referring to these figures, the apparatus therein illustrated comprises a wheeled carriage 6 adapted to be moved over or along the work-piece W.

If desired, the wheels I of the carriage may run on a suitable track 8. The carriage is propelled in a manner well understood in the art by a motor (not shown) which causes the carriage to move forwardly at thedesired uniform speed. The carriage'has a bracket 9 secured to it, a part I0 of which, or a separate part attached to the bracket, constitutes a guide plate for the torch holder shown at II. The torch holder has transversely extending arms l2 (Fig. 3) which slide on the guide plate 10 and carry pins l3 which are guided in a pair of parallel slots 14 in the plate. A torch H is mounted in the holder and-extends downwardly through a central relatively wide slot I5 in the guide plate so that its tip T is in proper relation to the surface of the work-piece as shown in Fig. 2. A link [6 pivotallyconnects the torch holder H to a rotary disc [1. This disc is rotated from an electric motor IS on the carriage through suitable reduction gearing in-the casing l9. Thus rotation of the disc I! by the motor :18 imparts a reciprocating or back and forth motion to the torch, the reciprocation being in the direction of movement of the carriage B as distinguished from reciprocation transversely of the direction of movement of the carriage.

Thetorch is supplied with oxygen, and fuel gas such as acetylene, and with cooling water, in the usual -way through suitable hoses indicatedat 20 .in Fig.2. When the surfaceportion of the workpiece is to-be hardened by the application of heat followed byquenching, a header 2! may be positioned behind the torch tip as shown in Fig.2 to apply quenching liquid, such as water, to the heated surface. The quenching header may be attached to the torch by means of a bracket 22 and supplied with quenching water through a hose 23. When-the quenching header is attached to the torchas shown in :Fig. 2 it reciprocates with the torch but if desired the quenching header maybe supported by the bracket-'9 in which case the reciprocating motion imparted to the torch is not imparted to the quenching header. Such an arrangement is shown in Fig. '7 in which simi lar parts of theapparatus-are designated'by the same reference characters primed.

In usingthe apparatus shown in Figs. 2 and 3 to carry out the method, the carriage is propelled .forwardlyzby its motor and the torch holder is simultaneously movedforwardly and backwardly ;with a-reciprocating motion by the separate motor 18. By varyingthe relative speeds of the two motors any desired sweepingmotion of the torch with a not forward motion can be obtained. The speed of the motor 18 may be controlled in any suitable way asby means of an adjustable cen- .trifugal speed control governor 24 of the type shown in'the patent to;C.1'I. Evans'No. 2,032,743. The motor which propels theearriage- Bmay also be provided with a similar governor.

Instead of employing a separate motor'to reciprocate the torch, the discill may begeared to the motor which propels the carriage.

Figs. 4, andfishowa modification of the apparatus suitable for use in the heat treatment of a work-piece W while'being'rotated in abench lathe indicated at 25. The carriage :26 of 'the lathe may bemoved alongtthe bed ofthe lathe by turning a hand wheel-'21. .The carriage'ZB has attached to it a plate;28 which supports thetorch and the means forreciprocating it .An. electric motor 2-9 on the plate :28. rotates .a disc 3!! through asuitable gear reduction unit 13!. -A.link32.pivctally connected to'the 'disc.30 reciprocates 'the torch in a manner similar to;that above described but in this case theitorchj holder ;33,-.to whichithe link :32 is pivotallyconnected,supports-the torch '33"I1 a horizontal position so that it projects over .the-work-piecewhere its tip T is in suitable position to direct the heating; flames against'its-surface. The guide: plated 4 for athes-torchz holder is mounted on suitable brackets 35 (Fig. 4) supported by the plate 28 and is slotted as shown at 36 (Fig. 5) to form a guide for pins 31 carried by laterally extending arms on the torch holder. A quenching header 38 may be supported by the torch or the plate 28 for directing a quenching liquid such as water against the surface of the work-piece after it has been heated by the torch.

In using the apparatus shown in Figs. 4 and 5 to carry out the method, the carriage 26 of the lathe is given a movement in the direction in which the net forward movement of the torch lengthwise of the work-piece is to take place. This movement of the carriage 26 corresponds to the movement of the carriage 6 along the track 8 in the form of apparatus shown in Figs. 2 and 3. If desired, of course, the carriage 26 may be motor operated. During movement of the carriage the motor 29 reciprocates the torch in the direction of movement of the carriage, i. e., lengthwise of the work-piece. By properly correlating the speed .of movement of the carriage 28 and the speed at which the torch is reciprocatedthe desired sweeping movement of the torch with a not forward motion along the length of the Work- =piece'W is obtained.

'In both forms of apparatus the torch holder is so guided during its reciprocation that the torch tip moves rectilinearly in a path parallel to the surface of the work-piece so that the distance from the tip to the work surface remains constant, this being important in heat treating apparatus of the present type to produce uniform heating of the work surface by the torch flames.

I claim: .1. The method of flamehardening or annealing the surface portion of metal work-pieces which comprises directing a system of flames against successive unit areas of the work surface, moving the flame system relative to the work surface with a series of forward strokes and intervening rearward strokes, the forward strokes being longer than the rearward strokes to produce a net forward movement of the flame system relative .to the work surface, and correlating the speed of movement of the system of flames with the flame intensity such that the flame system is moved :fromapreceding unit area of the surface portion being treated to the next unit area before the preceding unit area has reached a burning temperaturawhereby each unit area is heated to the desired extent and to the desired depth.

:2. In the heat treatment of the surface portion of metal workpieces by means of flames, the method of obtaining deeppenetration of the heat into the work-piece without burning or melting its surface which comprises intermittently applying the-flames to unit areas of the work surface .by. alternate relatively long forward and relatively short rearward movement of the flames relative tothe work surface until the net forward movement of the flames relative to the work surface completes treatment of an area of the work surface throughout the desired distance, and correlating the speed of movement of the system of flames with the flame intensity such that the flame system is moved from a, preceding unit area of the surface portion being treated to the next unit area before the preceding unit area has reached -a burning temperature, whereby each unit area is heated to the desired extent and to the desired depth.

3. The method of flame hardening or annealing a surface portion-of metal work-pieces which comprises directing a flame system against the surface of the work-piece, moving one of the flame system and the work-piece relative to the other with a series of alternating forward and rearward strokes, the forward strokes being longer than the rearward strokes to produce a net forward movement, and so correlating the rate of progression of the heating with the flame intensity that the flame system is relatively moved from a preceding unit area of the surface portion being treated to the next unit area before the preceding unit area has reached a burning temperature, whereby each unit area is heated to the desired extent and to the desired depth.

4. The method of flame hardening or annealing a surface portion of metal work-pieces which comprises directing a flame system against the surface of the work-piece, moving one of the flame system and the work-piece relative to the other with a series of alternating forward and rearward strokes, the forward strokes being longer than the rearward strokes to produce a net forward movement, so correlating the rate of progression of the heating with the flame intensity that the flame system is relatively moved from a preceding unit area of the surface portion being treated to the next unit area before the preceding unit area has reached a burning temperature, whereby each unit area is heated to the desired extent and to the desired depth, and applying a quenching fluid to the successively heated unit areas after they have been heated to the desired extent and to the desired depth.

5. The method of hardening the surface portion of metal work-pieces which comprises directing a flame system against the surface of the Work-piece, moving the flame systemrelative to the work-piece with a series of alternating forward and rearward strokes, the forward strokes being longer than the rearward strokes to produce a net forward movement of the flame system relative to the Work, so correlating the rate of progression of the heating with the flame intensity that the flame system is moved from a preceding unit area of the surface portion being treated to the next unit area before the preceding unit area has reached a burning temperature, whereby each unit area is heated to the desired extent and to the desired depth, and applying a quenching liquid to the successively heated unit areas after they have been heated to the desired extent and to the desired depth.

6. The method of hardening the surface portion of metal work-pieces which comprises directing a flame system against the surface of the work-piece, moving the flame system relative to the work-piece with a series of alternating forward and rearward strokes, the forward strokes being longer than the rearward strokes to produce a net forward movement of the flame system relative to the Work, so correlating the rate of progression of the heating with the flame intensity that the flame system is moved from a preceding unit area of the surface portion being treated to the next unit area before the preceding unit area has reached a burning temperature, whereby each unit area is heated to the desired extent and to the desired depth, continuously moving a quenching head in the direction of the forward movement of the flame system, and in the rear thereof, at a rate substantially equal to the rate of net forward movement of the flame system, and projecting a quenching liquid from said quenching head onto the successively heated unit areas of the work-piece after they have been heated to the desired extent and to the desired depth.

JOHN J. CROWE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,959,650 Verity May 22, 1934 2,076,515 Kinzel Apr. 6, 1937 2,321,645 Bishop et a1 June 15, 1943 OTHER REFERENCES Metals Handbook, 1939 edition, published by American Society for Metals, pages 930-933, 

